it's 18% for people who identify themselves as romney voters. gary nurenberg reports on the increasing number of small undecided voters that are the ones being targeted during tonight's debate. >> reporter: the romney and obama campaigns agree on this. >> it is about the 4%, 5% of people who really have not been paying much attention to the campaign who haven't made up their minds. >> reporter: american university professor. >> anything is possible but in order for it to have real impact, romney would have take some rinks and obama would have to make some mistakes. >> reporter: romney risking alienating the republican right. >> i don't think they would stay home but might give him less money. >> reporter: still important for the ongoing ad war. >> people say that romney should come in with some zingers and try to make obama lose his cool. >> reporter: zingers make debate history. '88 vice presidential when dan quail was comparing him to jack kennedy. >> senator, you're no jack kennedy. >> but here's the punch line of that. who won the election?